I had an Aiwa stereo/receiver several years ago that could tune the FM radio in 50kHz increments instead of 200kHz. Most stations were weaker 50kHz off, but a few were stronger. More interestingly, there were one or two stations I could only get on the even decimals, usually between two empty odds. Now I wonder if someone's transmitter was configured incorrectly, or whether it was an illegal broadcast.